Influencing factors of time from thyroidectomy to bone metastasis for differentiated thyroid carcinoma

Objective To investigate the factors which influence the time from thyroidectomy to bone metastasis for differentiated thyroid carcinoma (DTC). Methods Forty patients treated in Chinese PLA General Hospital from January 2008 to June 2016 and diagnosed with bone metastases resulting from DTC were enrolled in our study. The factors which influenced the time from thyroidectomy to bone metastasis for DTC were analyzed by Wilcoxon test, life table analysis and Cox regression analysis. Results The time from thyroidectomy to bone metastasis for DTC was 6.6±1.1 (0.5-28) years. Univariable analysis revealed that patients with extrathyroid extension (P=0.033) and multifocal lesions (P=0.012) had shorter time to metastasis. Multivariable Cox analysis revealed that extrathyroid extension (HR=2.138, P=0.033) and multifocal lesions (HR=2.293, P=0.018) influenced the metastasis. Conclusion Extrathyroid extension and multifocal lesions are the independent factors that influence the time from thyroidectomy to bone metastasis for DTC.